Ohki Yasushi, Ikawa Yoshiya, Shiraishi Hideaki, Inoue Tan
Graduate School of Biostudies, Kyoto University, Kyoto 606-8502.
J Biochem. 2002 Nov;132(5):713-8. doi: 10.1093/oxfordjournals.jbchem.a003278.
The Tetrahymena group I intron ribozyme folds into a complex three dimensional structure for performing the self-splicing reaction. Catalysis depends on its core structure comprising two helical domains, P4-P6 and P3-P7. The two domains are joined by three sets of conserved base-triple(s) and other tertiary interactions. We found that the disruption of J8/7 X P4, one such conserved base-triple, causes the catalytic ability to deteriorate without altering the folding rate. This suggests that the base-triple stabilizes the active structure of the ribozyme but plays no significant role in RNA folding. By combining the present and previous results, it can be concluded that three sets of conserved base-triples play distinct roles in the Tetrahymena ribozyme.
嗜热四膜虫I组内含子核酶折叠成复杂的三维结构以进行自我剪接反应。催化作用取决于其核心结构，该结构由两个螺旋结构域P4 - P6和P3 - P7组成。这两个结构域通过三组保守的碱基三联体和其他三级相互作用连接在一起。我们发现，破坏其中一个这样的保守碱基三联体J8/7 X P4会导致催化能力下降，而不会改变折叠速率。这表明碱基三联体稳定了核酶的活性结构，但在RNA折叠中没有显著作用。结合目前和先前的结果，可以得出结论，三组保守碱基三联体在嗜热四膜虫核酶中发挥着不同的作用。
